Forsaken Miner

This creature can't block.
Whenever you commit a crime, you may pay {B}. If you do, return this card from your graveyard to the battlefield. (Targeting opponents, anything they control, and/or cards in their graveyards is a crime.)

Lord Skitter, Sewer King

Whenever another Rat you control enters, exile up to one target card from an opponent's graveyard.
At the beginning of combat on your turn, create a 1/1 black Rat creature token with "This token can't block."

Rottenmouth Viper

As an additional cost to cast this spell, you may sacrifice any number of nonland permanents. This spell costs {1} less to cast for each permanent sacrificed this way.
Whenever this creature enters or attacks, put a blight counter on it. Then for each blight counter on it, each opponent loses 4 life unless that player sacrifices a nonland permanent of their choice or discards a card.

Nezumi Linkbreaker

When this creature dies, create a 1/1 red Mercenary creature token with "{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery."

Deep-Cavern Bat

Flying, lifelink
When this creature enters, look at target opponent's hand. You may exile a nonland card from it until this creature leaves the battlefield.

Haywire Mite

When this creature dies, you gain 2 life.
{G}, Sacrifice this creature: Exile target noncreature artifact or noncreature enchantment.

Mudflat Village

{T}: Add {C}.
{T}: Add {B}. Spend this mana only to cast a creature spell.
{1}{B}, {T}, Sacrifice this land: Return target Bat, Lizard, Rat, or Squirrel card from your graveyard to your hand.

Swamp

Homicide Investigator

Whenever one or more nontoken creatures you control die, investigate. This ability triggers only once each turn. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Hopeless Nightmare

When this enchantment enters, each opponent discards a card and loses 2 life.
When this enchantment is put into a graveyard from the battlefield, scry 2.
{2}{B}: Sacrifice this enchantment.

Case of the Stashed Skeleton

When this Case enters, create a 2/1 black Skeleton creature token and suspect it. (It has menace and can't block.)
To solve — You control no suspected Skeletons. (If unsolved, solve at the beginning of your end step.)
Solved — {1}{B}, Sacrifice this Case: Search your library for a card, put it into your hand, then shuffle. Activate only as a sorcery.

Experimental Confectioner

When this creature enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Whenever you sacrifice a Food, create a 1/1 black Rat creature token with "This token can't block."

Spiteful Hexmage

When this creature enters, create a Cursed Role token attached to target creature you control. (If you control another Role on it, put that one into the graveyard. Enchanted creature is 1/1.)

Tangled Colony

This creature can't block.
When this creature dies, create X 1/1 black Rat creature tokens with "This token can't block," where X is the amount of damage dealt to it this turn.

Insatiable Avarice

Spree (Choose one or more additional costs.)
+ {2} — Search your library for a card, then shuffle and put that card on top.
+ {B}{B} — Target player draws three cards and loses 3 life.

Greedy Freebooter

When this creature dies, scry 1 and create a Treasure token. (To scry 1, look at the top card of your library. You may put that card on the bottom. A Treasure token is an artifact with "{T}, Sacrifice this token: Add one mana of any color.")